Osteomalacia is a serious impediment to rehabilitation of patients with chronic renal failure treated by dialysis. Preliminary studies indicate an increased chondroitin sulfate content in osteomalacic dialysis bone. This finding fits theories of mineralization which proposes that chondroitin-sulfate protein complexes must be degraded before mineralization can occur. We propose studies to test this hypothesis. Biochemical studies will amplify our preliminary quantitative findings and determine whether bone of dialysis patients has abnormal chondroitin sulfate-sialoprotein complexes. Immunohistochemical studies will determine whether these complexes have abnormal morphological relationships to mineral deposits in dialysis bone. Finally, osteoblast cultures will show whether these complexes inhibit mineralization of bone matrix and whether the inhibition is reversed as they are degraded.